The invention relates to a constant velocity universal joint or coupling provided with an outer ring having a socket, an inner ring accommodated in the socket, and a set of flatted balls accommodated in groove-like ball races formed in the surface of the socket and the surface of the inner ring respectively, to transmit rotation from the one ring to the other ring.
An example of such a universal joint or coupling is disclosed by British patent 1.500.768.
This known coupling is provided further with a cage placed between the outer ring and the inner ring, the case having apertures in which the balls are accommodated. This cage aligns or steers the balls in the bisecting plane. The balls then lie with their faces against flat sides of the apertures and their spherical portions against regular ball race in both the outer ring and the inner ring.
The object of the invention is to provide a universal coupling of simplified construction and assembly. For this purpose, the universal coupling according to the invention is characterized in that a ball with its flat face can freely cooperate with the curved surface of a ball race. "Freely" means that no specific element such as a pin or the like engages the ball with a coupling ring.
As a result, the coupling according to the invention can lack a cage for steering or aligning the balls, and it has been found that by the specific placement of the flat portion of the balls directly on the races, a self-aligning action, as it were, is obtained between the balls and the races during rotation. It has been found that this favorably affects the operation of the coupling, as for example by producing virtually silent rotation under load and flexible compensation of load variations at various angles.
Specifically, the coupling according to the invention may be so constructed that the flat face of the balls is in rotary and/or displaceable cooperation with the curved surface of the ball race of the inner ring. At the same time, the coupling according to the invention may be so constructed that the curved surfaces of the ball races of the inner ring, cooperating with the flat faces of the balls, are turned convex side outward in axial section.
Further, the coupling according to the invention may be so constructed that the curved surface of each ball race of the inner ring, cooperating with the flat face of the balls, are straight lines in planes perpendicular to the axis of rotation of the inner ring, which lines are perpendicular to the central axial plane of the ball race.
Further, the coupling according to the invention may be so constructed that a ball lock ring is mounted on the outer face of the inner ring, with bearing spring members projecting into the ball races of the inner ring. The coupling according to the invention has the additional advantage that assembly, owing to the absence of a cage for the ball, can be carried out in a more convenient manner, namely axially.
Alternatively, the coupling according to the invention may be so constructed that, on the outer end of the outer ring, over the opening of the socket in the outer ring, a yielding sealing ring is arranged, extending to the inner ring or the lock ring.
The invention will now be described with reference to the drawings, showing a preferred embodiment of the universal coupling of the invention by way of example.